GE employee mentions NCG's in CA units.

This is when we want access to internal memos....the way that diary entry is written gives me the impression it was a major issue. In fact I wonder if GE charged CA owners for the purging; knowing full well it was the design that caused it. A bit like the car recalls of today perhaps?
But from the large amount of CA's around today, still in use, or used until recently, it's clear a lot of them didn't overly suffer from NCG's.
I'd like to know what the proportion is of CA's manufactured, to those that needed frequent purging, and were an inconvenience to GE. Just going on ebay ads, it does seem that for surviving examples, CA's are not represented much less than CK's, taking into account the longer production time for the CK.

That's an interesting question. The way the purging instructions are worded, it seems one purge is normal, but if it's required again in another month, then that isn't, and a leak is indicated. There's no indication given as to an acceptable frequency, or if as you say, it should be a one off thing.

Perhaps the surviving examples did have a couple of purges in their early life, and haven't needed it since. That there was a CA form A mentioned in the Flickr group that had solder in the access valve threads suggests some have never been purged.

Something else I've wondered about is if the NCG's keep coming from the methyl formate, and not a leak, does that mean eventually the methyl formate stops working - once there's nothing left to break down into the NCG's? (Not that it will happen in our lifetime of course).
Or, is there only a certain amount that breaks down for a given quantity, and once gone, the methyl formate is then "pure"? Unfortunately, my knowledge of chemisty is next to nothing, so I'm not sure on that one.
Old refrigeration servicing journals in a library that still keeps old books might be the only way to find out.

Service Manual
General Electric
Refrigerators
with
Ca Machines can be downloaded from Archive.org
Be sure to change the FORMAT if necessary to read it.
1933 and 1934